The Fatigue Research Of Frame Brackets Of Bulk Carrier

Fatigue failure is one of the major failure modes of ship structures. The problem about fatigue failure is crucial, especially for large vessels and ships, where the material of high strength steel is used. In recently half century, fatigue has been paid more attention by engineering field and mechanics field. Fatigue strength analyses, prediction of fatigue life and assessment about fatigue behaviors have important engineering background and particular theoretic value. The research aim of this subject is to study the fatigue behaviors caused by different structural details, based on the traditional theory of ship structures design. After studying fatigue strength about different ship structural details, this paper is to find some ship structural details which have applied value, and to achieve the purpose of theory combined with engineering practice.The paper main study the simplified method for calculating the fatigue strength based on fatigue strength theory of ship structural details, also study the finite element method for calculating the stress concentration factors of ship structural details. The main aspects studied in this paper are as follows:1. According to China Classification Society(CCS)'s "Rules and Regulations for the Construction and Classification of Sea-going Steel Ships", four types of main frame's brackets are designed for 42000DWT bulk carrier.2. Based on "Guide for Fatigue Strength of Ship Structures" which was issued by CCS in 2001, the 42000DWT bulk carrier's frame brackets fatigue strength are calculated and compared in the condition of four different brackets,applying finite element method(FEM) and the simplified calculation measure of S-N curve method. The method for calculating the stress concentration factors of brackets is researched.3. Shape optimization for bracket is studied, by means of the Random Designs and the Sub-problem method by ANSYS Software.With the achievement of the research aim of this subject, this paper will be promoting the progress of fatigue strength assessment of ship engineering structures, and the designed ship structural details have much applied value.